Geoscience Reference
In-Depth Information
GLOBAL SEA-LEVEL
ERA
PERIOD
CLIMATE, ENVIRONMENTS AND ROCKS OF
'BRITISH ISLES'
GLOBAL
TECTONICS
Age
(Ma)
LATITUDE
falling
rising
0
20
40
60
60°
N
QUATERNARY
Ice house. Ice sheets. permafrost. Glacigenic sediments
Warm temperature. Estuarine and marine
sediments in Southeast.
Humid, sub-tropical weathering
Volcanoes in western Scotland. 'Mediterranean'
TERTIARY
50°
80
100
120
140
160
180
200
220
240
260
Warm, arid. Marine transgression draws warm
tropical ocean over most of Britain. Chalk - fine
grained pure marine carbonates. 'Bermuda'
CRETACEOUS
40°
Warm, humid. Coarse grained
siliciclastic fluvial+deltaic sediments.
Fine grained marine muds and
limestones in deeper water. 'Gulf of Mexico'
JURASSIC
30°
Age
10
9
years
EON
Warm/hot, arid. Coarse terrestrial siliciclastic
sediments + evaporites. 'Sahara'
Hot, arid. Deserts - sand seas, evaporite basins.
Hypersaline basin in N. Sea area.
'Arabia/Persian Gulf'
TRIASSIC
20°
0
PERMIAN
280
300
320
340
360
380
PHANEROZOIC
Equatorial, humid. Limestone reefs in clear water
give way to coastal swamps and deltaic
conditions with coal and silicislastic sediments.
Cornish granite emplacement. 'Amazon delta'
CARBONIFEROUS
10°
1.0
Warm, arid. Terrestrial siliciclastic sediments in
northern deserts, marine siliciclastic sediments
in south. 'Australian Desert'
Warm, sub-tropical. Shales and limestones
(including reefs) in marine
environments. 'Australian Barrier Reef'
Temperate-warm marine environments, siliciclastic
sediment. Volcanic arc, volcanoclastic sediments
and batholiths in Wales, Lake District,
E. Ireland + S. Scotland N.W. Scotland
'
docks' with Britain. 'New Zealand'
PROTEROZOIC
DEVONIAN
400
420
440
460
480
0°
2.0
SILURIAN
3.0
10°
ORDOVICIAN
ARCHAEAN
500
520
540
560
580
4.0
Temperate. Marine environments.
Fine and coarse grained siliclastic sediments,
some limestones.
20°
CAMBRIAN
HADEAN
4.6
30
S
PROTEROZOIC
PRECAMBRIAN
Metamorphic belt (Lr. Palaeozoic/Proterozoic)
Volcanic rocks (basalts, tuffs etc.)
intrusive igneous rocks (granites, etc.)
Tertiary clays and sands
Cretaceous chalk, clays, sands
Jurassic limestones, clays
Triassic sandstone
Carboniferous limestones, sands, shales
Permian
Devonian sandstones
Lower Palaeozoic marine sediments
0
100
km
Figure 10.20
A geological time scale, with the principal stratigraphy, regional geology and palaeo-environments of the British
Isles. Modern analogues for Britain's past environments are given.
Source: after Harland et al. (1982), map partly after Lovell (1977)
